Necropsy findings are described in 8 Newfoundland dogs from the same colony with discrete subaortic stenosis. Infective endocarditis involving the aortic valve occurred in 4 dogs and in each it proved fatal. Damage to the aortic-valve cusps by the jet of blood ejected through the discretely narrowed left ventricular outflow tract predisposes to the development of infective endocarditis in both dogs and humans with discrete subaortic stenosis.